Ganglion

William C. Shiel Jr., MD, FACP, FACR

Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

What is a ganglion?

A ganglion is a sac-like swelling or cyst formed from the tissue that
lines a joint or tendon. The tissue, called synovium, normally
functions to produce lubricating fluid for these areas. A ganglion
is a cyst formed by the synovium that is filled with a thick jelly-like fluid. While ganglia can follow local trauma to the tendon or
joint, they usually form for unknown reasons. Occasionally, ganglia
are early signs of arthritis that will become more obvious in the future.

Where do ganglia form and what symptoms do they cause?

Ganglia can form around any joint, but they are most frequently found
in the wrist and ankles. They are usually painless and often barely
visible as localized swellings. They typically do not appear to be inflamed. The largest ganglions form behind the back of the knee, causing a sense of fullness or tightness. A ganglion here is referred to as a Baker cyst, after the doctor who originally described the condition.

How are ganglia treated?

A ganglion can spontaneously rupture and go away. Other treatment
options include removal of the ganglion fluid with a
needle and syringe (aspiration) with or without an injection of cortisone
medication. Occasionally, the entire ganglion is resected with
surgery. People with a persisting or recurring ganglion should be evaluated for signs of systemic forms of arthritis, such as rheumatoid arthritis.